Evaluation Method for Crystal Defect in Silicon Single Crystal Wafer

Abstract

The present invention provides an evaluation method for a crystal defect in a silicon single crystal wafer based on an infrared laser scattering tomograph method, wherein at least, the silicon single crystal wafer is irradiated with a laser beam, and light that enters the silicon single crystal wafer is scattered by a crystal defect, and the scattered light is detected to evaluate a Direct Surface Oxide Defect (DSOD) and a void defect smaller than the DSOD in the silicon single crystal wafer. As a result, the evaluation method for a crystal defect in a silicon single crystal wafer that can simply and precisely evaluate, e.g., a small DSOD, which can be conventionally evaluated based on a Cu deposition method alone, without requiring a wasteful cost.

Description

TECHNICAL FIELD[0001]The present invention relates to an evaluation method for a crystal defect in a silicon single crystal wafer that serves as a substrate for manufacturing, e.g., a semiconductor integrated circuit.BACKGROUND ART[0002]Silicon single crystal wafers are used mostly as materials forming a semiconductor integrated circuit. Various kinds of stresses are applied to a wafer by a heat treatment or machining until a semiconductor device is formed on a surface layer of a silicon single crystal wafer to provide an integrated circuit. Therefore, a silicon single crystal wafer produced from a silicon single crystal obtained by a Czochralski method (which will be referred to as a CZ method hereinafter) is superior in strength, and hence this wafer tends to be often used.[0003]However, in recent years, with density growth of an integration degree of a semiconductor integrated circuit and attendant miniaturization of a device circuit, a quality requirement for a silicon single cr...

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Benefits of technology

[0009]In view of the above-explained problem, it is an object of the present invention to provide an evaluation method for evaluating a crystal defect in a silicon single crystal wafer, which can simply and precisely evaluate, e.g., a small DSOD that can be conventionally evaluated by the Cu deposition method alone without requiring a wasteful cost.

Problems solved by technology

However, it has been revealed that very small crystal defects are present even in a silicon single crystal subjected to crystal growth in a neutral region to suppress such crystal defects.

Since such a crystal defect has a very small defect size (a diameter: approximately 15 nm to 20 nm), a particle counter used for regular crystal examination cannot detect such crystal defects.

However, when the wafer is rejected on this stage, wafer machining is performed even with respect to a rejected lot without exception, and the rejected product takes labor and cost like a conforming product but is finally discarded, which is hence wasteful.

Furthermore, the defect is hard to be discriminated from, e.g., a scratch caused by machining, and hence there is a problem in a measurement precision.

This small void defect may also affect characteristics of an integrated circuit formed on the surface layer of the silicon single crystal wafer in some cases.

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